In addition, EGCG has been shown to PARP inhibitor cause G0/G1 cell cycle arrest and apoptosis of human epidermoid carcinoma cells (Ahmad et al., 1997 and Ahmad et al., 2000). Furthermore, EGCG treatment of human epidermoid carcinoma cells resulted in induction of cyclin kinase inhibitors such as CDKN1, which through downregulation of cyclins D1 and D2 and cyclin-dependent

kinases (cdk2, cdk4, and cdk6) causes G0/G1 cell cycle arrest, ultimately culminating in apoptotic cell death (Ahmad et al., 2000). In agreement with these data, we demonstrate that all tested compounds induced up regulation of CDKN1A and down regulation of cdk2 and cdk4. Analysis of genes encoding members of the BCL-2 family showed that, although treatment with unmodified EGCG resulted in increased expression of the BCL2 (B-cell CLL/lymphoma 2) gene, treatment with biotransformed EGCG or biotransformed green tea extract suppressed the expression

of this gene. In contrast, the only significant effect on the expression of the BCL2L1 (BCL2-like 1) gene was the suppression A-1210477 mouse of its expression by the biotransformed green tea extract. These results showed the superiority of the biotransformed samples in down-regulating the expression of these genes, reducing the generation of BCL-2 proteins, which function in inhibiting apoptosis. Leone et al. (2003) showed that green tea catechins are very potent inhibitors of the antiapoptotic Bcl-2 family proteins Bcl-xL and Bcl-2, suggesting a strong link between the anticancer activities of these tea polyphenols and their inhibition of a crucial antiapoptotic pathway. As this pathway has been implicated in the development of many human malignancies, the reduction of the expression of these genes is considered a pro-apoptotic function (Yang & Wang,

2011). In addition, EGCG has been Cobimetinib manufacturer shown to induce apoptosis in S180 cells by altering the G2/M phase of the cell cycle through down-regulation of the oncogenes c-myc and bcl-2 (Manna, Banerjee, Mukherjee, Das, & Panda, 2006). Subsequently, Thyagarajan, Zhu, and Sliva (2007) showed that EGCG suppressed the expression of the oncogene c-myc in breast cancer cells. Our findings demonstrate that all tested compounds significantly down regulated the expression of c-myc. A key regulator of the G1/S phase transition in the cell cycle is the retinoblastoma (pRb) tumour suppressor protein (Nevins, Leone, DeGregori, & Jakoi, 1997). Members of the retinoblastoma family suppress cell growth, at least in part, by inhibiting E2F-dependent transcription of genes whose products are required for DNA synthesis and/or cell cycle progression (Nevins et al., 1997 and Parreño et al., 2001).